Implanted functional electrical stimulation hand system in adolescents with spinal injuries: an evaluation

Safety and Feasibility of Cervical and Thoracic Transcutaneous Spinal Cord Stimulation to Improve Hand Motor Function in Children With Chronic Spinal Cord Injury

OBJECTIVE

In adults with cervical spinal cord injury (SCI), transcutaneous spinal stimulation (scTS) has improved upper extremity strength and control. This novel noninvasive neurotherapeutic approach combined with training may modulate the inherent developmental plasticity of children with SCI, providing even greater improvements than training or stimulation alone. Because children with SCI represent a vulnerable population, we first must establish the safety and feasibility of any potential novel therapeutic approach. The objectives of this pilot study were to determine the safety, feasibility, and proof of principle of cervical and thoracic scTS for short-term effect on upper extremity strength in children with SCI.

MATERIALS AND METHODS

In this nonrandomized, within-subject repeated measure design, seven participants with chronic cervical SCI performed upper extremity motor tasks without and with cervical (C3-C4 and C6-C7) and thoracic (T10-T11) site scTS. Safety and feasibility of using cervical and thoracic sites scTS were determined by the frequency count of anticipated and unanticipated risks (eg, pain, numbness). Proof-of-principle concept was tested via change in force production during hand motor tasks.

RESULTS

All seven participants tolerated cervical and thoracic scTS across the three days, with a wide range of stimulation intensities (cervical sites = 20-70 mA and thoracic site = 25-190 mA). Skin redness at the stimulation sites was observed in four of 21 assessments (19%) and dissipated in a few hours. No episode of autonomic dysreflexia was observed or reported. Hemodynamic parameters (systolic blood pressure and heart rate) remained within stable limits (p > 0.05) throughout the assessment time points at baseline, with scTS, and after the experiment. Hand-grip and wrist-extension strength increased (p < 0.05) with scTS.

CONCLUSIONS

We indicated that short-term application of scTS via two cervical and one thoracic site is safe and feasible in children with SCI and resulted in immediate improvements in hand-grip and wrist-extension strength in the presence of scTS.

CLINICAL TRIAL REGISTRATION

The Clinicaltrials.gov registration number for the study is NCT04032990.

A Systematic Review of the Scientific Literature for Rehabilitation/Habilitation Among Individuals With Pediatric-Onset Spinal Cord Injury

Objectives

To conduct a systematic review to examine the scientific literature for rehabilitation/habilitation among individuals with pediatric-onset spinal cord injury (SCI).

Methods

A literature search of multiple databases (i.e., PubMed/MEDLINE, CINAHL, EMBASE, PsychINFO) was conducted and was filtered to include studies involving humans, published as full-length articles up to December 2020, and in English. Included studies met the following inclusion criteria: (1) ≥50% of the study sample had experienced a traumatic, acquired, nonprogressive spinal cord injury (SCI) or a nontraumatic, acquired, noncongenital SCI; (2) SCI onset occurred at ≤21 years of age; and (3) sample was assessed for a rehabilitation/habilitation-related topic. Studies were assigned a level of evidence using an adapted Sackett scale modified down to five levels. Data extracted from each study included author(s), year of publication, country of origin, study design, subject characteristics, rehabilitation/habilitation topic area, intervention (if applicable), and outcome measures.

Results

One hundred seventy-six studies were included for review (1974-2020) with the majority originating from the United States (81.3%). Most studies were noninterventional observational studies (n = 100; 56.8%) or noninterventional case report studies (n = 5; 2.8%). Sample sizes ranged from 1 to 3172 with a median of 26 (interquartile range [IQR], 116.5). Rehabilitation/habilitation topics were categorized by the International Classification of Functioning, Disability and Health (ICF); most studies evaluated ICF Body Function. There were 69 unique clinical health outcome measures reported.

Conclusion

The evidence for rehabilitation/habilitation of pediatric-onset SCI is extremely limited; nearly all studies (98%) are level 4-5 evidence. Future studies across several domains should be conducted with novel approaches to research design to alleviate issues related to sample sizes and heterogeneity.

Assessment of the upper limb of the tetraplegic patient

The aim of our study is to describe the assessment of the upper limb in tetraplegic patients to follow his (her) neurological progression and to define the medical or surgical treatment program. We selected upper limb assessment tools and scales for tetraplegic patients described in the medical literature through a PubMed search over the last four decades. For each method, we present the implementation rules and its metrological properties, including its validity in French. We selected five clinical scales for functional evaluation of grasping, as well as four scales for evaluating the overall function of these patients. Finally, we identified three complementary precision assessment tools. The AIS (ASIA Impairment Scale) classification describes the level and the severity of the spinal cord lesion. The Giens classification is more practical for describing the upper limb in middle and low tetraplegia. Impairments can be assessed with most common generic scales and nonspecific measurement devices: range of motion, strength, sensory loss, spasticity, joint pain. Measurement of pinch and grip strength is widely used and easy to perform. The Capabilities of Upper Extremity (CUE) and the Jebsen Taylor Test are the best validated and usable scales. At a general functional level, the Spinal Cord Independence Measure (SCIM) is the most relevant scale in these patients. Motor nerve blocks, electromyography, movement analysis and echography are promising additional methods. Assessment of the upper limb of tetraplegic patients relies both on generic and specific assessment tools and scales.

A Review of Different Stimulation Methods for Functional Reconstruction and Comparison of Respiratory Function after Cervical Spinal Cord Injury

Background

Spinal cord injury (SCI) is a common severe trauma in clinic, hundreds of thousands of people suffer from which every year in the world. In terms of injury location, cervical spinal cord injury (CSCI) has the greatest impact. After cervical spinal cord injury, the lack of innervated muscles is not enough to provide ventilation and other activities to complete the respiratory function. In addition to the decline of respiratory capacity, respiratory complications also have a serious impact on the life of patients. The most commonly used assisted breathing and cough equipment is the ventilator, but in recent years, the functional electrical stimulation method is being used gradually and widely.

Methods

About hundred related academic papers are cited for data analysis. They all have the following characteristics: (1) basic conditions of patients were reported, (2) patients had received nerve or muscle stimulation and the basic parameters, and (3) the results were evaluated based on some indicators.

Results

The papers mentioned above are classified as four kinds of stimulation methods: muscle electric/magnetic stimulation, spinal dural electric stimulation, intraspinal microstimulation, and infrared light stimulation. This paper describes the stimulation principle and application experiment. Finally, this paper will compare the indexes and effects of typical stimulation methods, as well as the two auxiliary methods: training and operation.

Conclusions

Although there is limited evidence for the treatment of respiratory failure by nerve or muscle stimulation after cervical spinal cord injury, the two techniques seem to be safe and effective. At the same time, light stimulation is gradually applied to clinical medicine with its strong advantages and becomes the development trend of nerve stimulation in the future.

Electrical stimuli in the central nervous system microenvironment

Electrical stimulation to manipulate the central nervous system (CNS) has been applied as early as the 1750s to produce visual sensations of light. Deep brain stimulation (DBS), cochlear implants, visual prosthetics, and functional electrical stimulation (FES) are being applied in the clinic to treat a wide array of neurological diseases, disorders, and injuries. This review describes the history of electrical stimulation of the CNS microenvironment; recent advances in electrical stimulation of the CNS, including DBS to treat essential tremor, Parkinson's disease, and depression; FES for the treatment of spinal cord injuries; and alternative electrical devices to restore vision and hearing via neuroprosthetics (retinal and cochlear implants). It also discusses the role of electrical cues during development and following injury and, importantly, manipulation of these endogenous cues to support regeneration of neural tissue.

Relationship between neurological injury and patterns of upright mobility in children with spinal cord injury

BACKGROUND

The predictors and patterns of upright mobility in children with a spinal cord injury (SCI) are poorly understood.

OBJECTIVE

The objective of this study was to develop a classification system that measures children's ability to integrate ambulation into activities of daily living (ADLs) and to examine upright mobility patterns as a function of their score and classification on the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) exam.

METHODS

This is a cross-sectional, multicenter study that used a convenience sample of subjects who were participating in a larger study on the reliability of the ISNCSCI. A total of 183 patients between 5 and 21 years old were included in this study. Patients were asked if they had participated in upright mobility in the last month and, if so, in what environment and with what type of bracing. Patients were then categorized into 4 groups: primary ambulators (PrimA), unplanned ambulators (UnPA), planned ambulators (PlanA), and nonambulators.

RESULTS

Multivariate analyses found that only lower extremity strength predicted being a PrimA, whereas being an UnPA was predicted by both lower extremity strength and lack of preservation of S45 pinprick sensation. PlanA was only associated with upper extremity strength.

CONCLUSIONS

This study introduced a classification system based on the ability of children with SCI to integrate upright mobility into their ADLs. Similar to adults, lower extremity strength was a strong predictor of independent mobility (PrimA and UnPA). Lack of pinprick predicted unplanned ambulation, but not being a PrimA. Finally, upper extremity strength was a predictor for planned ambulation.

Spinal cord injuries in children and adolescents

This chapter provides an overview of spinal cord injuries (SCI) in children and adolescents, including epidemiology, medical and musculoskeletal complications, rehabilitation and psychosocial aspects. Males are more commonly affected than females during adolescence; however, as the age at injury decreases, the preponderance of males becomes less marked, and by 3 years of age the number of females with SCIs equals that of males. The neurologic level and degree of completeness varies with age; among children injured prior to 12 years of age approximately two-thirds are paraplegic and approximately two-thirds have complete lesions. Among adolescents, approximately 50% have paraplegia and 55% have complete lesions. Management of pediatric-onset SCI should be family centered and developmentally based, responsive to the dynamic changes that occur during growth and development. Distinctive anatomical and physiological features of children and adolescents, along with growth and development, are responsible for unique manifestations and complications of pediatric SCI. SCI without radiological abnormalities (SCIWORA), birth injuries, lap-belt injuries, upper cervical injuries, and the delayed onset of neurological deficits are relatively unique to pediatric SCI. Children who sustain their SCI before puberty experience a higher incidence of musculoskeletal complications, such as scoliosis and hip dislocation.

Outcomes of urinary diversion in children with spinal cord injuries

PURPOSE

To gain a better understanding of the outcomes of the Mitrofanoff procedure for urinary diversion in children with spinal cord injury (SCI).

DESIGN

Descriptive retrospective.

PARTICIPANTS/METHODS

Individuals 6 to 27 years of age with SCI with at least 1 year follow-up after the Mitrofanoff procedure. Objective data collected via retrospective chart review include general demographics and medical/surgical history. Data collected via structured telephone interview include history of adverse urological events, bladder management, bladder management independence scores, patient satisfaction, and quality of life.

RESULTS

Sixteen subjects (13 female, 3 male) with a mean age of 19 years (range 6-27 y) who underwent the Mitrofanoff procedure were interviewed. Length of postoperative follow-up ranged from 1 to 8 years (mean 4.25 y). Complications included stomal stenosis 25% (n=4) with a mean of 19 months to first occurrence of stenosis; urethral incontinence 75% (n=12); renal/bladder calculi 19% (n = 3); and stomal leakage 44% (n=7). Independence scores for bladder management after the Mitrofanoff procedure improved in 84% of subjects with tetraplegia and 25% of subjects with paraplegia. Eighty-eight percent (n 14) were satisfied with the procedure, while 12% (n=2) were somewhat satisfied. A thematic analysis of quality of life revealed that freedom (35%) and independence (35%) were most commonly cited.

CONCLUSION

While some subjects experienced complications, satisfaction was relatively high and level of independence in bladder management was greatly improved. This study demonstrates that the Mitrofanoff procedure is a beneficial option to improve independence and ease of bladder management in children with SCI.

Functional Electrical Stimulation for Neuromuscular Applications

Paralyzed or paretic muscles can be made to contract by applying electrical currents to the intact peripheral motor nerves innervating them. When electrically elicited muscle contractions are coordinated in a manner that provides function, the technique is termed functional electrical stimulation (FES). In more than 40 years of FES research, principles for safe stimulation of neuromuscular tissue have been established, and methods for modulating the strength of electrically induced muscle contractions have been discovered. FES systems have been developed for restoring function in the upper extremity, lower extremity, bladder and bowel, and respiratory system. Some of these neuroprostheses have become commercialized products, and others are available in clinical research settings. Technological developments are expected to produce new systems that have no external components, are expandable to multiple applications, are upgradable to new advances, and are controlled by a combination of signals, including biopotential signals from nerve, muscle, and the brain.

Exercise as a Health-Promoting Activity Following Spinal Cord Injury

Spinal cord injury is a catastrophic event that immeasurably alters activity and health. Depending on the level and severity of injury, functional and homeostatic decline of many body systems can be anticipated in a large segment of the paralyzed population. The level of physical inactivity and deconditioning imposed by SCI profoundly contrasts the preinjury state in which most individuals are relatively young and physically active. Involvement in sports, recreation, and therapeutic exercise is commonly restricted after SCI by loss of voluntary motor control, as well as autonomic dysfunction, altered fuel homeostasis, inefficient temperature regulation, and early-onset muscle fatigue. Participation in exercise activities also may require special adaptive equipment and, in some instances, the use of electrical current either with or without computerized control. Notwithstanding these limitations, considerable evidence supports the belief that recreational and therapeutic exercise improves the physical and emotional well-being of participants with SCI. This article will examine multisystem decline and the need for exercise after SCI. It will further examine how exercise might be used as a tool to enhance health by slowing multisystem medical complications unique to those with SCI. As imprudent exercise recommendations may pose avoidable risks of incipient disability, orthopedic deterioration, or pain, the special risks of exercise misuse in those with SCI will be discussed.

Quantifying the passive extensibility of the flexor pollicis longus muscle in people with tetraplegia

STUDY DESIGN

Repeat measures design.

OBJECTIVE

The purpose of this study was firstly, to describe a simple clinical tool that can be used to measure the extensibility of the flexor pollicis longus (FPL) muscle; secondly, to test its reliability; and thirdly, to attain some 'normative' data of the extensibility of the FPL muscle in a representative sample of people with tetraplegia.

SETTING

A spinal cord injury unit in Sydney.

SUBJECTS

A total of 37 people (62 hands) with C4-C7 tetraplegia.

MAIN OUTCOME MEASURES

Angle of the carpometacarpal (CMC) joint of the thumb was measured in all subjects with the application of a series of thumb extensor torques. A device specifically designed for this purpose was used to standardize the torque and objectively quantify the CMC joint angle. In addition, repeat measurements were taken 3-5 days later in one subgroup of 13 subjects (one hand per subject) and 3 months later in another subgroup of 13 subjects (one hand per subject).

ANALYSIS

Intraclass correlation coefficients and percent close agreement scores were derived to quantify the 3-5 days and 3-month reliability between repeat measurements.

RESULTS

The median CMC angle of the thumb with the application of a 0.044 Nm torque was 63 degrees (range, 20-93 degrees). The intraclass correlation coefficients with the application of a 0.044 Nm torque were 0.88 (95% CI, 0.65-0.96) for measurements taken 3-5 days apart, and 0.90 (95% CI, 0.67-0.97) for measurements taken 3 months apart.

CONCLUSION

This study describes a simple and reliable way of measuring the extensibility of the FPL muscle in people with tetraplegia. This assessment tool and the 'normative' data provided in this study can be used to further investigate the contribution of the passive mechanical properties of the FPL muscle to hand function of people with C6 and C7 tetraplegia.

[Assessment of functional abilities, handicap and quality of life in patients with spinal cord injuries]

OBJECTIVES

A literature review of the methods of evaluating function, handicap and quality of life in patients with spinal cord injuries.

METHODS

The literature review was based on the available French and English articles published since 1990 in 3 databases: MEDLINE, Pascal and Embase.

RESULTS

The literature is dominated by descriptions of tools for evaluating functional limitations in motor deficiencies. Such descriptions involve the validation of generic tools for patients with spinal cord injuries or of specific tools during the evaluation of a particular intervention such as surgery of the tetraplegic hand or adaptation of technical help.

CONCLUSION

The tools to assess patients with spinal-cord injuries are sufficiently numerous and varied to allow us to evaluate physical, functional and psychosocial dimensions. Rigorous methodological validation is continuously at the base of those proposed tools and thus reinforces our choice to use them. Unfortunately, few evaluation tools for patients with spinal cord injuries have been published, translated into French and validated.

Transcutaneous functional electrical stimulation for grasping in subjects with cervical spinal cord injury

STUDY DESIGN

Case series.

OBJECTIVES

To evaluate the benefit, shortcomings and acceptance of a new transcutaneous functional electrical stimulation (FES) technology aimed at improving the grasp function in tetraplegic subjects in acute and postacute rehabilitation.

SETTING

Spinal cord injury (SCI) centre, university hospital.

METHODS

: Subjects (N=11) with complete or incomplete SCI at C4/5-C7 who started FES 1-67 months after their accident were included. Hand function tests, analysis of video recordings and of written documentation of FES sessions, status of muscle strength, and follow-up query were used as outcome measures.

RESULTS

Nine subjects used FES as a neuroprosthesis. Eight demonstrated improved grasp function and performance in activities of daily living. In one subject, no benefit from FES was observed. Two other subjects showed improvements in muscle strength and facilitation of active movement with FES. Four subjects successfully integrated FES as neuroprosthesis in everyday life within the rehabilitation centre. Three received the system for home use. The most relevant reasons for stopping the FES application were: (i) improvement of voluntary grasp function, (ii) physical and psychological problems, (iii) no available stimulator for home use, and (iv) insufficient assistance for electrode placement at home. Shortcomings related to the transcutaneous surface technology (eg pain or coactivation of neighbouring muscles) could usually be reduced, or did not limit the efficiency or acceptance of FES. Individually designed digital or analogue control devices were preferred.

CONCLUSION

Tetraplegic subjects in acute and postacute rehabilitation can profit from a new transcutaneous FES system with respect to functional use and independence. It can be implemented in the rehabilitation programme for muscle strengthening and facilitation of voluntary activity. For a successful application of FES, there is a need for individual electrode placement, stimulation programmes, and FES control devices.

Tetraplegia Hand Activity Questionnaire (THAQ): the development, assessment of arm-hand function-related activities in tetraplegic patients with a spinal cord injury

STUDY DESIGN

Development of Tetraplegia Hand Activity Questionnaire (THAQ).

SETTING

Patients and spinal cord injury (SCI) professionals from five rehabilitation centres in the Netherlands and Belgium.

OBJECTIVE

To construct a disease-specific questionnaire to evaluate interventions to the arm-hand of tetraplegics in terms of gained and lost activities relevant to the patient.

METHODS

All arm-hand function-related activities were inventoried by examining existing scales and interviewing spinal cord injury patients and professionals in the field. Subsequently, item reduction was achieved; first, in the technical construction by incorporating all activities in an item list, then reducing the list by selecting the items most likely to be sensitive to change after surgical or functional electro stimulation interventions on the arm-hand as judged by an expert panel, using a Delphi method.

RESULTS

The arm-hand-related activity inventory comprised 652 activities. The technical construction of the items and the Delphi procedure resulted in a questionnaire with 153 items. The experts considered many of the 'new' activities more relevant for the evaluation of hand function interventions than those found in scales studied in the literature. This is reflected in a relatively large proportion of new activities (69%) for the item list of the THAQ, and even more in the domains work/admin/telecom (88%) and leisure (100%).

CONCLUSION

The questionnaire constructed to assess hand function-related activities contains relevant activities to evaluate arm-hand function-related interventions for tetraplegic SCI patients.

Use of the ICF conceptual framework to interpret hand function outcomes following tendon transfer surgery for tetraplegia

STUDY DESIGN

Clinical commentary

OBJECTIVE AND SETTING

This paper is a clinical commentary based on the Round Table discussion on Assessment and Outcomes at the 7th International Conference on Tetraplegia: Surgery and Rehabilitation, Bologna, Italy 6-8 June, 2001. It refers specifically to the 10-year re-review undertaken in 2001 at the Spinal Unit, Burwood Hospital, Christchurch, New Zealand.

SUBJECTS

In all, 24 tetraplegic persons at a minimum of 12 years and up to 18 years following bilateral forearm tendon transfer surgery.

METHOD

The data were interpreted using the International Classification of Functioning, Disability, and Health (ICF) conceptual framework as the basis of interdisciplinary understanding of the participation dimension.

RESULTS

The results of the study outlined confirm that outcome measurement at more than one level of functioning is desirable to determine the functional effects beyond grip strength levels and activities of daily living, to consider the dimension of participation.

CONCLUSIONS

Use of the ICF as a theoretical framework for interpretation of the results enhanced the clinical applicability of the outcome measures used in the 10-year re-review undertaken in New Zealand in 2001.

Implanted neuroprostheses for restoration of hand function in tetraplegic patients

Restoration of hand function through functional electrical stimulation allows tetraplegic patients to use existing abilities to control paralyzed muscles. In patients with C5 or C6 spinal cord injuries, implanted upper extremity neuroprostheses use functional electrical stimulation technology to power hand and arm muscles. A variety of devices, often using contralateral shoulder motion, sends signals via a small external controller and transmitting coil to an implanted stimulator. The stimulator powers designated upper extremity muscles via implanted electrodes. The surgical procedure is minimally invasive and easily reversed. Palmar and lateral grasp, among other functions, can be reliably restored, leading to significant improvements in functional capacity. High user satisfaction, low complication rates, and recent advances in technology and control systems contribute to the success of this technology in the treatment of devastating spinal cord injuries.

Analyse critique des modalités d’évaluation des résultats de la chirurgie fonctionnelle du membre supérieur tétraplégique. Revue de la littérature sur les 50 dernières années

OBJECTIVE

To study the methods of assessment of upper limb functional surgery in the literature.

METHODS

The literature review relating to the years 1950-2002 was carried out with three data bases: Medline, Pascal, Embase. This review also involved a thorough study of non-indexed references.

RESULTS

Although many instruments or tests are used to assess outcome after surgery, their reliability, validity and responsiveness have not been adequately proven. Methodology appears to be the major failing of the various scales used to assess these patients. The conceptual models underlying the evaluation are all too often unspecified. There is a lack of pertinence of the selected tasks for tetraplegics. There is limited documentation of the guiding framework or conceptualisation. Furthermore, the process of item selection is often unknown. Scales or instruments are also deemed to be too insensitive to document the small but meaningful functional gains made by tetraplegics after functional surgery.

CONCLUSION

To answer the need for a specific assessment tool for tetraplegics who undergo functional surgery, we have developed a national, multicenter, prospective and longitudinal study based on two concepts: the first concept is related to Life Habits that are the activities of daily living and social roles recognised by the socio-cultural context of a person according to age, sex and social and personal identity. They include activities that should be accomplished on a daily basis (nutrition, fitness, personal care, communication, mobility, etc.). Life Habits presenting a significant level of disruption can create handicap situations. The second concept is in relation with Motor Capacities that correspond to the abilities of a patient to perform basic and functional tasks regardless of contextual factors (environmental and personal factors).

Exercise Recommendations for Individuals with Spinal Cord Injury

Persons with spinal cord injury (SCI) exhibit deficits in volitional motor control and sensation that limit not only the performance of daily tasks but also the overall activity level of these persons. This population has been characterised as extremely sedentary with an increased incidence of secondary complications including diabetes mellitus, hypertension and atherogenic lipid profiles. As the daily lifestyle of the average person with SCI is without adequate stress for conditioning purposes, structured exercise activities must be added to the regular schedule if the individual is to reduce the likelihood of secondary complications and/or to enhance their physical capacity. The acute exercise responses and the capacity for exercise conditioning are directly related to the level and completeness of the spinal lesion. Appropriate exercise testing and training of persons with SCI should be based on the individual's exercise capacity as determined by accurate assessment of the spinal lesion. The standard means of classification of SCI is by application of the International Standards for Classification of Spinal Cord Injury, written by the Neurological Standards Committee of the American Spinal Injury Association. Individuals with complete spinal injuries at or above the fourth thoracic level generally exhibit dramatically diminished cardiac acceleration with maximal heart rates less than 130 beats/min. The work capacity of these persons will be limited by reductions in cardiac output and circulation to the exercising musculature. Persons with complete spinal lesions below the T(10) level will generally display injuries to the lower motor neurons within the lower extremities and, therefore, will not retain the capacity for neuromuscular activation by means of electrical stimulation. Persons with paraplegia also exhibit reduced exercise capacity and increased heart rate responses (compared with the non-disabled), which have been associated with circulatory limitations within the paralysed tissues. The recommendations for endurance and strength training in persons with SCI do not vary dramatically from the advice offered to the general population. Systems of functional electrical stimulation activate muscular contractions within the paralysed muscles of some persons with SCI. Coordinated patterns of stimulation allows purposeful exercise movements including recumbent cycling, rowing and upright ambulation. Exercise activity in persons with SCI is not without risks, with increased risks related to systemic dysfunction following the spinal injury. These individuals may exhibit an autonomic dysreflexia, significantly reduced bone density below the spinal lesion, joint contractures and/or thermal dysregulation. Persons with SCI can benefit greatly by participation in exercise activities, but those benefits can be enhanced and the relative risks may be reduced with accurate classification of the spinal injury.

Command control for functional electrical stimulation hand grasp systems using miniature accelerometers and gyroscopes

Recent commercially available miniature sensors have the potential to improve the functions of functional electrical stimulation (FES) systems in terms of control, reliability and robustness. A new control approach using a miniature gyroscope and an accelerometer was studied. These sensors were used to detect the linear acceleration and angular velocity of residual voluntary movements on upper limbs and were small and easy to put on. Five healthy subjects and three cervical spinal cord injured subjects were recruited to evaluate this controller. Sensors were placed on four locations: the shoulder, upper arm, wrist and hand. A quick forward-and-backward movement was employed to produce a distinctive waveform that was different from general movements. A detection algorithm was developed to generate a command signal by identifying this distinctive waveform through the detection of peaks and valleys in the sensor's signals. This command signal was used to control different FES hand grasp patterns. With a specificity of 0.9, the sensors had a success rate of 85-100% on healthy subjects and 82-97% on spinal cord injured subjects. In terms of sensor placement, the gyroscope was better as a control source than the accelerometer for wrist and hand positions, but the reverse was true for the shoulder.

Restoration of movement using functional electrical stimulation and Bayes' theorem

Various computational approaches have been applied to predict aspects of animal behavior from the recorded activity of populations of neurons. Here we invert this process to predict the requisite neuromuscular activity associated with specified motor behaviors. A probabilistic method based on Bayes' theorem was used to predict the patterns of muscular activity needed to produce various types of desired finger movements. The profiles of predicted activity were then used to drive frequency-modulated muscle stimulators to evoke multijoint finger movements. Comparison of movements generated by electrical stimulation with desired movements yielded root mean squared errors between approximately 18 and 26%. This reasonable correspondence between desired and evoked movements suggests that this approach might serve as a useful strategy to control neuroprosthetic systems that aim to restore movement to paralyzed individuals.

Improvements in activities of daily living following functional hand surgery for treatment of lesions to the cervical spinal cord: self-assessment by patients

STUDY DESIGN

Tetraplegic patients were tested for hand strength before and after hand surgery. They also answered questions about how they rated the results of surgery.

OBJECTIVES

Presentation of the efficacy of reconstruction of hand raising, lateral grip, and cylindrical grip in the tetraplegic hand.

SETTING

The study was conducted in the Werner Wicker Clinic, Bad Wildungen, Germany, from 1991 to 1998.

METHODS

The results of reconstruction surgery performed on 23 tetraplegic hands, as reflected in lifting the hand (n=3), lateral grip (n=21), and cylindrical grip (n=14), are presented. In a follow-up study in 22 patients, their management of activities of daily living 34.1 months (9-51 months) after the surgery is compared with the preoperative situation. Subjective satisfaction levels were elicited for each of the 22 patients by means of a questionnaire.

RESULTS

The gain in force corresponded to 893 g (150-1500 g) for cyclindrical grip and 488 g (100-1200 g) for lateral grip, while they were able to develop grade 4 force for lifting the hand. After the operation 28 aids/appliances that patients had formerly used regularly were no longer necessary. There were 75 separate activities listed in the questionnaire, and on average the 22 patients were able to perform 8.7 (0-20) more of these. Most patients (19) said they would advise others to have the operation and 18, that they would have the operation again. There were 12 complications in nine patients.

CONCLUSION

Reconstructive surgery on the hands of tetraplegic patients leads to gains in both cylindrical grip and lateral grip force and to increased manual dexterity. Patient satisfaction with the procedure is high.

Percutaneous Freehand system intramuscular electrode placement

The FreeHand (NeuroControl Corporation, USA) system is an implantable electronic neuroprosthesis designed to stimulate muscles of tetraplegic upper limbs to achieve lateral pinch and simple grasp. When first introduced, the system required insertion through multiple large incisions, but recently introduced intramuscular electrodes have allowed the development of a percutaneous electrode placement technique. The technique minimizes incisions, decreases overall operative time and patient morbidity and improves the outcome by minimizing tendon adhesions.

Indications and future directions for upper limb neuroprostheses in tetraplegic patients: a review

The development of the upper extremity neuroprosthesis has been a challenging and rewarding contribution to the management of the SCI patient. The authors' experience and that of their clinical trial teams has verified that this technology is a strong alternative to conventional reconstruction and conservative management. In the future, even more powerful tools will emerge from the laboratory as these devices and collaborative surgical procedures evolve.

Evaluation of upper extremity motor function tests in tetraplegics

OBJECTIVE

To provide an overview of arm-hand function tests useful in tetraplegic subjects. Considerations for selection of an appropriate test are also provided.

DATA SOURCES

A Medline literature search was conducted covering the period from 1967 to March 2001. Relevant references cited in the selected papers were also considered, regardless of the year of publication.

STUDY SELECTION

This review was restricted to strength tests, functional and ADL tests. Only general tests and tests designed specifically to test tetraplegic persons written in English, or in Dutch were included in the review.

RESULTS

Information is provided on four types of strength tests, 10 general and five specific functional tests and eight ADL tests.

CONCLUSION

Many tests are available to measure upper extremity motor function in tetraplegics. Selection of a test is at first determined by the outcome value in which the investigator is interested. When the type of outcome value has been determined, the most suitable test has to be selected from the range of available tests. When two tests appear to be equally suitable, the availability of information on psychometric properties of the test when used in tetraplegic patients is a decisive factor. When information on the reliability, validity and sensitivity of a test is missing, it should be gathered before using the test.

Management of the paralyzed elbow in tetraplegia

The management of the paralytic conditions in tetraplegia requires understanding neural pathophysiology. A comprehensive rehabilitative and surgical plan requires a multidisciplinary approach. Prior to redistributing the muscle forces across the elbow, a supple osseo-articular platform must be created. The authors recommend PDT and BTT transfers and a FES neuroprosthesis. Future work in this field will advance the application of neuromodulation and its deployment in different neurophysiologic states.

Neuroprostheses for the upper extremity

Functional electrical stimulation (FES) neuroprostheses can be used to replace lost motor and sensory function in persons with neurological disorders. FES technology has subsequently been shown effective and safe in restoring hand function in adults with spinal cord injury. The freehand system consists of an implanted receiver-stimulator, an external shoulder position sensor, and an external control unit. Commands are originated by voluntary movement of the contralateral shoulder and are measured by the sensor. There are several types of electrodes: epimysial, intramuscular, nerve cuff, and intraneural. Neuroprostheses are recommended within the context of all available reconstructive options for the upper limbs. Voluntary tendon transfers are the first choice. The clinical outcomes as measured by improvement on scales of impairment, activities of daily living, and satisfaction are rewarding. The next step in improvement of the motor function of person with spinal cord injury will be the addition of a controllable second upper extremity and the elimination of additional external hardware.

Postural arm control following cervical spinal cord injury

This study used estimates of dynamic endpoint stiffness to quantify postural arm stability following cervical spinal cord injury (SCI) and to investigate how this stability was affected by functional neuromuscular stimulation (FNS). Measurements were made in the horizontal plane passing through the glenohumeral joint on three SCI-impaired arms, which ranged in functional level from a weak C5 to a strong C6. Endpoint stiffness, which characterizes the relationship between externally imposed hand displacements and the resultant forces, was estimated during the application of planar, stochastic perturbations to each arm. These estimates were used in conjunction with voluntary endpoint force measurements to quantify stability and strength during voluntary contractions and during voluntary contractions in the presence of triceps FNS. The primary findings were: 1) the differences in the force generating capabilities of these arms were due primarily to differences in shoulder strength; 2) measurements of strength alone could not be used to predict arm stability; and 3) triceps FNS improved postural arm stability for all tested conditions. These results suggest strategies for improved control of FNS systems designed to restore arm function following cervical SCI and underscore the importance of examining the effects of FNS on both strength and stability.

Efficacy of an implanted neuroprosthesis for restoring hand grasp in tetraplegia: a multicenter study

OBJECTIVE

To evaluate an implanted neuroprosthesis that allows tetraplegic users to control grasp and release in 1 hand.

DESIGN

Multicenter cohort trial with at least 3 years of follow-up. Function for each participant was compared before and after implantation, and with and without the neuroprosthesis activated.

SETTING

Tertiary spinal cord injury (SCI) care centers, 8 in the United States, 1 in the United Kingdom, and 1 in Australia.

PARTICIPANTS

Fifty-one tetraplegic adults with C5 or C6 SCIs.

INTERVENTION

An implanted neuroprosthetic system, in which electric stimulation of the grasping muscles of 1 arm are controlled by using contralateral shoulder movements, and concurrent tendon transfer surgery. Assessed participants' ability to grasp, move, and release standardized objects; degree of assistance required to perform activities of daily living (ADLs), device usage; and user satisfaction.

MAIN OUTCOME MEASURES

Pinch force; grasp and release tests; ADL abilities test and ADL assessment test; and user satisfaction survey.

RESULTS

Pinch force was significantly greater with the neuroprosthesis in all available 50 participants, and grasp-release abilities were improved in 49. All tested participants (49/49) were more independent in performing ADLs with the neuroprosthesis than they were without it. Home use of the device for regular function and exercise was reported by over 90% of the participants, and satisfaction with the neuroprosthesis was high.

CONCLUSIONS

The grasping ability provided by the neuroprosthesis is substantial and lasting. The neuroprosthesis is safe, well accepted by users, and offers improved independence for a population without comparable alternatives.

An implantable upper extremity neuroprosthesis in a growing child with a C5 spinal cord injury

OBJECTIVES

To implement a functional electrical stimulation (FES) hand neuroprosthesis called the Freehand System in a growing child with spinal cord injury (SCI) using extra lead wire to accommodate limb growth, and to evaluate the performance of the Freehand System during the subject's maturation.

SETTING

Pediatric orthopedic hospital specializing in SCI rehabilitation.

SUBJECT

Ten-year-old female patient with a C5 level SCI.

METHOD

The Freehand System was implanted. Eight electrodes were implanted to targeted forearm and hand muscles to provide grasp and release function. The lead wire associated with each electrode was pathed subcutaneously up the arm with 4 cm of extra lead distributed throughout the path to accommodate expected limb growth. All leads were attached to a stimulator placed in the upper chest. Measures of lead unwinding, limb growth, stimulated muscle strength, and hand function were made at 6 and 16 months after implant.

RESULTS

By 16 months post implant, the upper limb growth plates were closed and humeral and radial bone growth combined was 2.7 cm from the time of surgery. For all eight leads, lead unwinding in the upper arm was approximately 1.2 cm and was comparable to humeral bone growth (1.4 cm). Lead unwinding in the lower arm was also measurable for the two electrodes in hand muscles. Six of eight electrodes maintained grade 3 or better stimulated muscle strength throughout the growth period according to a manual muscle test. Of the two other electrodes, one appeared to have lost function due to depletion of excess lead. However, hand function with FES was comparable at 6 and 16 months post implant suggesting that growth did not negatively impact performance with the FES system. Hand function with FES was improved over voluntary hand function as well. Using the Freehand System, a pinch force of approximately 15 N was achieved compared to 1.3 N of voluntary tenodesis pinch force. Scores on the Functional Independence Measure (FIM) increased by 9 points when FES was used as compared to voluntary function. Improvements occurred primarily in eating and grooming. Independence in writing was achieved only with FES.

CONCLUSIONS

For this child, hand function with the Freehand System was sustained over the growth period and was a significant functional improvement over voluntary hand function. By using excess lead wire, the Freehand System was successfully implemented before skeletal maturity, affording the child improved hand function earlier than would be otherwise indicated.

Functional control of the hand in tetraplegics based on residual synergistic EMG activity

A microprocessor controlled device (MeCFES) was used for the investigation of the possibility of restoring hand function in C5 tetraplegics with paralysis of the hand. To date, 3 tetraplegics have been testing the system. The myoelectric signals from wrist extension were recorded and used as control signals for functional electrical stimulation (FES) of thumb adduction/flexion. The results have shown that the device can improve the hand function of tetraplegics. In this part of the work, a hand function test was designed and used to assess the results.

Implantable electrode lead in a growing limb

An implantable electrode leadwire system used to provide limb function for individuals with spinal cord injuries (SCI's) was evaluated in a series of growing dogs to determine whether it could maintain its performance in the presence of growth. Thirty implantable electrodes (15 epimysial and 15 intramuscular) were implanted in the forelimb muscles of six young dogs. The electrodes' leads were tunneled subcutaneously and anchored proximally in the shoulder with excess lead incorporated into the subcutaneous space to accommodate growth. Six of the leads had some of this excess placed in pouches made from surgical membrane while the other 24 leads had excess placed freely within the subcutaneous space. Motor responses to the electrodes were tested before and after growth with tendon force transducers and were compared to the performance of new electrodes implanted to the same muscles of the mature dog during the explant procedure. Measured were the pulse duration at which a measurable force is first produced (threshold) and the percentage of the maximum force that could be attained from the target muscle before activation of adjacent muscles (usable force range). An analysis of variance indicated that there was no difference in the usable force range (p = 0.62) of the original electrodes before and after growth and that of the new electrodes placed at maturity. There was a difference in the threshold (p = 0.001) which can be attributed to an increase in the values measured from the original electrodes after growth. However, the increase in threshold with growth averaged 6 micros which is not clinically significant and can be accommodated through stimulation programming. Growth of the limb and unwinding of excess lead were quantified by radiograph. Extension of the freely placed excess lead was comparable to growth so that the pouch enclosures were found to be unnecessary for facilitating lead expansion. By radiograph and surgical observations, only two of 30 electrodes (both intramuscular) appeared to have been subjected to lead tension, although they continued to provide adequate motor responses. Insufficient excess lead was judged to be the cause of dislodgment for one of these electrodes. Results of this study suggest that for this implantable leadwire system, excess lead placed in the subcutaneous space can unwind on demand with limb growth such that an electrode will remain in position and provide a stable motor response.

A study of shoulder motions as a control source for adolescents with C4 level SCI

This study quantitatively examined and compared the shoulder motions of C4 level spinal cord injury (SCI), C5 level SCI, and able-bodied persons as a command source. The study was motivated by both the success of shoulder control in functional electrical stimulation (FES) systems designed for C5 level SCI people and the lack of quantitative information on the shoulder motion of persons with C4 level SCI. A dual-axis transducer was used to monitor the elevation/depression and protraction/retraction angles of each subject's shoulder while they performed three experimental sections which examined: the range of active shoulder motion; the ability to move incrementally to discrete positions with the aid of visual feedback; and the ability to hold discrete shoulder positions for an extended period without visual feedback. Results indicated that each group had the largest average shoulder displacements (abled = 23 degrees +/- 4 degrees, C5's = 14 degrees +/- 3 degrees, and C4's = 9 degrees +/- 3 degrees) while attempting to elevate and that on average the C4 group had the smallest range of active shoulder motion. No statistically significant differences between the groups were found in either the accuracy or stability of reaching discrete positions with the aid of visual feedback or in the accuracy of holding discrete shoulder positions for an extended period without visual feedback. The results suggest that within their limited range of motion the individuals with C4 level SCI retained shoulder control sufficient for use as an neuroprosthetic command interface.

Muscle fatigue from intermittent stimulation with low and high frequency electrical pulses

OBJECTIVE

To evaluate muscle fatigue resulting from intermittent low frequency and high frequency stimulation for the application of closed-loop control in functional electrical stimulation (FES).

DESIGN

Nonrandomized trial.

SETTING

General community, a referral center, institutional practice, and ambulatory care.

PATIENTS

Twenty healthy nondisabled men volunteered for the normal muscle group. Four paraplegic men with implanted percutaneous intramuscular electrodes for FES volunteered for the paralyzed muscle group.

INTERVENTION

The stimulation frequency was set at low (20 Hz) or high (100 Hz). Stimulation was administered in 4-second bursts at the start of 60-second, 120-second, and 240-second periods (duty cycles of 1/15, 1/30, and 1/60, respectively).

MAIN OUTCOME MEASUREMENTS

Knee extensor torques were measured during intermittent electrical stimulation. A strength decrement index (SDI) was used to assess muscle fatigue. Actual knee extensor torques in the paraplegic men were also measured with an isokinetic dynamometer.

RESULTS

Muscle fatigue was significantly greater at 20 Hz than at 100 Hz for both the nondisabled and the paraplegic subjects (p < .0001). Muscle fatigue at the 1/15 cycle was significantly reduced (p < .01).

CONCLUSIONS

Muscle fatigue was greater at the lower frequency (20 Hz) than at the higher frequency (100 Hz) during intermittent electrical stimulation, suggesting that intermittent high frequency stimulation may be valuable in the development of closed-loop control strategies for FES.